Author
Topic: Where Does The Fizz Go In A Shaken can ? (Read 1895 times)

As a sheepy i of course luff fizzy drinks. Fizzy pop is all I think about from the moment I wake up to the time I fall asleep.

Look, here's a can of fizzy pop !

A can Of Fizzy Pop Just Moments ago !

Please don't confuse the can with Eric the cabbage:

Eric the cabbage - not to be confused with a can of fizzy pop !!

Why is that when I shake my can of pop and then leave it for a while the fizz that would normally explode has settled ? Where has all that extra fizz gone ? Did it go back into fizzy-goodness drinky ?..If so..how ?

Please answer this question as I have to attend a lecture on the "A lecture regarding the cavity between the uppermost level of fizzy pop and the top of the can" and I would like to turn up with this little soupcon of knowledge to make me look klevur.

As long as the integrity of the can is unchanged, if one leaves the can alone long enough, the history of the can (whether it had been shaken, dropped, frozen, etc.) should be irrelevant to the state of the contents. It should reach an equilibrium, in which the amount of dissolved CO2 depends only on the contents of the can (which should not change as long as the can stays closed). If the can is at equilibrium, then shaking it should not change much other than mixing the gaseous and liquid phases.

It's also not entirely clear to me that shaking the can does much other than create bubbles by virtue of the mechanical mixing of liquid and gaseous phases. Imagine a can that is filled 90% of the way with water, and the remainder is helium at a reasonable pressure above standard pressure. The solubility of helium is very small in water, compared to CO2, so the amount that goes into or out of solution can be essentially disregarded compared to the amount in the headspace. If this can were allowed to stand such that the gaseous and liquid phases are perfectly separated, sharing only a simple interface, then opening the can would allow the compressed helium to escape, but not result in any liquid discharge. If, however, the can were shaken immediately prior to opening, the phases would mix such that there would be bubbles of helium within the liquid phase. As soon as the pressure is released, all of the bubbles will expand, taking some of the liquid with them as the helium escapes.

When the gas considered is switched to CO2, then we also have to consider the effect of gas coming out of solution when the can is opened. I guess the bubbles created by shaking would catalyze the evolution of CO2, somewhat like the effect of mentos--but I think that most of liquid that comes out of a recently shaken then opened can has to do with the quantity of gas being under the liquid rising and expanding when the pressure is released.

As long as the integrity of the can is unchanged, if one leaves the can alone long enough, the history of the can (whether it had been shaken, dropped, frozen, etc.) should be irrelevant to the state of the contents. It should reach an equilibrium, in which the amount of dissolved CO2 depends only on the contents of the can (which should not change as long as the can stays closed). If the can is at equilibrium, then shaking it should not change much other than mixing the gaseous and liquid phases.

It's also not entirely clear to me that shaking the can does much other than create bubbles by virtue of the mechanical mixing of liquid and gaseous phases. Imagine a can that is filled 90% of the way with water, and the remainder is helium at a reasonable pressure above standard pressure. The solubility of helium is very small in water, compared to CO2, so the amount that goes into or out of solution can be essentially disregarded compared to the amount in the headspace. If this can were allowed to stand such that the gaseous and liquid phases are perfectly separated, sharing only a simple interface, then opening the can would allow the compressed helium to escape, but not result in any liquid discharge. If, however, the can were shaken immediately prior to opening, the phases would mix such that there would be bubbles of helium within the liquid phase. As soon as the pressure is released, all of the bubbles will expand, taking some of the liquid with them as the helium escapes.

When the gas considered is switched to CO2, then we also have to consider the effect of gas coming out of solution when the can is opened. I guess the bubbles created by shaking would catalyze the evolution of CO2, somewhat like the effect of mentos--but I think that most of liquid that comes out of a recently shaken then opened can has to do with the quantity of gas being under the liquid rising and expanding when the pressure is released.

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